The Contractor shall serve as a clinical center for the investigation of selected patient groups from the Cooperative Study of Sickle Cell disease (CSSCD). The Contractor shall collaborate with other CSSCD investigators and NHLBI staff in the development and implementation of a protocol to continue to follow the newborn cohort and patients surviving beyond age thirty-five. The principal objective of this contract is to continue to follow the newborn cohort of patients presently being followed in the CSSCD to better understand severity, onset of early organ damage, and risk factors contributing to certain complications and outcome. This study is also intended to follow another important cohort of patients surviving beyond age thirty-five to better understand longevity and causes of death.